When the geographic coverage area of a mobile communication network is wide, there are still areas that remain outside the coverage area and for which it is not viable or even possible to build a base network or the usage of a network is not permitted, for example, for safety reasons. However, even in these areas the reachability of people becomes important. Reachability can mean setting up a conventional phone call, but increasingly it also means setting up other types of contacts, such as video conferences, text-based conversations etc. either individually or connected together.
Redirecting calls (call forward) within a mobile communication network (GSM/GPRS) or between a mobile communication network and a public switched telephone network (PSTN) is generally known. When the user wants to direct calls to another number, he/she must activate call forwarding on his/her phone. In call forwarding, a new target number where the calls are redirected to is determined. The phone number can be another mobile phone number, a number of a telephone network or the number of a switch center. The new target address is updated in the Home Location Register (HLR) in the mobile communication network, after which the routing to the new number can be done. Call forwarding can be performed only to individual voice, data and fax calls. Thus forwarding different message types is not necessarily discussed and, for example, forwarding short messages is not possible. The solutions also do not discuss how the contacts are switched to systems outside the coverage area (of the public switched telephone network or the mobile communication network) and to numbers which are not known by the user setting up the call forwarding. In other words, in solutions according to prior art, setting up call forwarding and determining the target numbers is the responsibility of the user.
For example, there are ships, airplanes and mines located outside the coverage area of a mobile communication network. In airplanes the usage of mobile phones is not permitted for safety reasons, unlike in ships, wherefrom there is no connection to base stations on open seas. Both, however, have passengers, for whom it may be important to be within reach also during the journey. In setting up the redirection the problem is the addresses/numbers of the terminals used in the ship (for example satellite phones), which should be known in advance (prior to leaving the coverage area) in order to set up redirection. Publication WO 0180449 A1 describes one way of setting up an interface between a satellite phone used in an airplane and a mobile phone. A user's identifier card (for example, the SIM card of a mobile phone or other suitable type for satellite phones) is placed in a reader in a satellite phone, after which a connection between the identifier system of the card of the satellite ground station and the mobile communication network of the card holder. In the mobile communication network there is a unit, with which it is possible to return the information that the terminal of the user is roaming in the home network, but at that particular moment “busy” to the mobile communication network. The identifier card in the reader of the satellite phone changes the user's existing call forwarding settings in such a manner that the phone call that was made is routed to a new number when the mobile communication network receives a BUSY-message from said unit. Card readers are required in the terminals used in the system according to the publication, in which case all communication systems cannot automatically function as targets for redirection.
As the mobile communication systems develop, contacts comprise more and more multimedia, in which case the problem is the redirection of contacts between two different communication systems. The solutions according to prior art do not discuss what information the network-terminal combination of the user is offering at a certain moment, i.e. how the direction of contacts according to the network and terminal is usually handled, as well as whether the call forwarding between the desired systems is even possible.